Inspection: Wastewater Pipeline, Stockport

United Utilities

United Utilities recently contacted us with a request for an aerial survey of a 250m elevated pipeline that serves a wastewater treatment plant in Stockport. It wanted to use the results of this inspection to determine repair and maintenance plans.

Pipe bridges and elevated sewers are often inspected manually, but this typically entails the use of scaffolding, which is slow to erect and therefore expensive. A UAV-based  inspection offered an opportunity to make significant time and cost savings.  In this case, overhead powerlines presented an additional  hazard and this lent further weight to the argument in favour of using a drone rather than metal scaffolding.

Following our usual risk assessment and safety checks, we conducted a full survey of the ‘hidden’ top-side of the pipeline. The process took just over half a day in all.

As requested, we supplied high resolution digital images and HD video. These enabled United Utilities engineers to gauge the condition of the pipeline along its entire length. They were able to identify one top-side defect that had not previously been logged, and to plan repair work accordingly. Conversely, they could see that one area they had suspected of leaking was in fact sound, as was the remainder of the 250m structure.

The photographic results also provided an excellent visual record of the condition of the pipe’s protective coating, and of the fixtures joining the pipe to its metal supports.

Assessing the value of the UAV-based approach, United Utilities Project Engineer James Devereux said: There were several advantages to using a drone for this inspection project. Most obviously, it allowed us to achieve in a couple of hours what might have taken around five days using scaffolding. That yielded considerable cost savings, and we were left with a complete visual record that we can refer back to in the future. Using the drone also delivers obvious safety benefits, especially in cases like this where power lines pass directly over the pipe.

There was also the question of being a good neighbour. Landowners usually don’t like having scaffolding on their fields, with all the physical disruption that building and moving it entails. Here, we finished the survey in a very short time and the field was left completely untouched.

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